Hey folks !
I'm pretty new to the subject 'communication'. I might sound a little stupid hope you don't mind. Anyway I'm participating a high-powered model rocket team and trying to communicate in about 8km distance with the rocket (it'll be high in the sky and the ground station will be on the ground obviously ) .We used to use 12dbi yagi antenna on the ground (Now I'm open for all antennas which suits the modules and provides the requirements). The communication will include floating data coming from various sensors. There will be about 10- 14 decimal number data such as gps latitude, longitude, altitude, pressure, temperature etc. Data will only flow through rocket to ground station.
I look up to LoRa SX1278 but it's not suitable to my case I guess. 0.3kbps > max 8km and that is probably the most optimistic case.
We are using TEENSY 4.1 on the rocket.
Not decided what to use on the ground station.
So can you guys help me to find a communication module both for my rocket and my ground station.
I'm open for any kind of help.
Thank you all 
I'd work out how many bytes you would be sending in 1 packet of data. Floats are 4 bytes (latitude & longitude). Assuming you won't exceed 65,535ft then altitude can be an unsigned 16-bit integer. Pressure and temperature can both be 16-bit integers, just multiplied up by factors of 10 (or another convenient value) etc.
The decide how many of those packets you need to send per second. That will give you your data rate. You may need to double or triple that to allow for retries (if you need them).
Then look for a radio system that will support that data rate over the required distance.
EDIT: Doesn't the TEENSY 4.1 have an on-board micro-SD holder? I've seen other discussions where the data is logged on the rocket and then retrieved after the flight (or several flights).
Competition requires live telemetry. I'm also saving it on the sd card. They want to see a new data package every 200ms. So the frequency must be 5hz
No idea where you got those figures from, but for ground to rocket or ground to balloon, they are rubbish, LoRa goes way way further and faster than that.
Look here;
Right at the end is some information on the higher data rates I got at long distances;
"Thus for one test, I used the higher data rates, bandwidth of 500Khz (BW500Khz) spreading factor 7 (SF7) and a coding rate of 4:8 (CR4:8) that gave an equivalent data rate of 13.7kbps according to the LoRa calculator. At my base station I received the above packets down to 7dBm at 105km, the distance was taken from the location in the previous tracker payload. Thus you could conclude that this 13.7kbps rate would have a range at 10mW of 150km."
And if UHF LoRa is not fast enough for you, there is 2.4Ghz LoRa;
"So with the simplest of antennas a pair of SX1280 LoRa® modules can communicate at 4.4km at 203kbs using only 12mW of transmit power, impressive."
2.4Ghz LoRa will run at circa 200,000bps at that distance with those antennas. And about 90km @ 2,000bps.
Thank you for the documentation.
However I guess I'm having trouble understanding.
So if I use SX1278 (is this module's properties change by different producers ?) with
[bandwidth of 500Khz (BW500Khz) spreading factor 7 (SF7) and a coding rate of 4:8 (CR4:8)] this properties I can reach 13.7kbps ?
And also is that enough for 5hz. I really can't understand that.
We used to have a Xbee module.That module had 10 and 80 kbps data rate options. When we used 80kbps , we were able to get about 58 bytes per package with 5Hz frequency at about 1 kilometers.
When we switched it to 10kbps option we communicated at 5km with about 1Hz frequency but it was only able to send 17 bytes.
I really don't understand anything about communication.
Do you have any suggestion for me to start understanding communication?
A website, youtube video etc. for me.
I'm studying Aerospace engineering so I don't really want to know everything about communication. It'll be perfect to just learn enough to launch the rocket.
BEWARE! You will not be processing any telemetry during the time the 512 byte block of data is being written to the SD card.
If you want this project to work at all, you will have to do some studying, and some experimentation. Or hire someone to do the technical part.
13,700bps is 1712bytes a second. You would likley be able to transmit 50-60 16byte packets a second at that rate. A LoRa packet can be up to 255 bytes.
Several articles on how much data you can send and how fast with LoRa here;
The articles on data and image transfers and ESP32CAM may be of interest.
And if you dont want to learn about the details of communication then you will likely need to employ someone to do it for you.
I actually did
I want to learn the details but not such as a electronics & communication engineer vise
Excellent! In this thread, you have been given some great pointers on how and where to start. I recommend the link in post #9.
Thank you a lot for the good documentation sir I think it really helped. About the SX1278 module's properties I will attach an image from the documentation.
EDIT: The operation range part confused me
Confused you temporarily, or permanently?
Now I wonder couple of things. I'd appreciate it if you can answer them.
1-) How can I know how much kilometers a module can reach ? (Mathematical formula etc. exists ? )
2-) How much, the byte in a package of a transmitter effects the range of communication? How can I know that or is there a formula.
3-) In the documentations you guys sent and other blogs I looked into, I never saw anything about in how much time the communication occur. Or how many packages the receiver gets in a second. Is that something I should know somehow or do I have to do experiments to find it.
4-) Let's say data rate is 13.4 kbps. It means 13400 bps. And that means 1675 bytes per second. Now here is the question: If I am transmitting 5 bytes of package. 1675/5 = 335 so theoretically is the receiver able to get 335 packages per second ?
5-) I saw people reach about 100k kilometers with 10kbps etc. Then how in the earth in the datasheet of the module it's written 8km with 2.4kbps. I saw stuff about bandwidth, spreading factor, coding rate, frequency and transmit power to effect the communication. Are those the ones what actually identifies the communication range.
6-) When I look the datasheet (again) the usage areas of the module is about systems with low data rate, slowly communicating and low byte transferring systems. Am I being stupid to use a SX1278 on a rocket ?
Woah that's a lot of question. I'm really sorry to bother you guys.
Thanks for everything.
Regard Eren
You might consider using Wi-Fi. Though normally considered short range, with line-of-sight it can go much further and the Tx power can be 100mW, or more depending on territory. Lots of people using Wi-Fi for long range broadband with directional antennas - traditionally using a Pringles can, but other designs can work better. See here: Directional Wifi antennas - Wifi-Highpower.co.uk and Long-range Wi-Fi - Wikipedia
One thing that puzzles me is the GPS aspect - I assume the flight is quite short, would a standard GPS module give fixes fast enough to be useful?
What does that mean. I guess temporarily ... 
Sure they exist. Consult a good communication textbook. However, radio waves are a physical thing, in a complex physical universe. They interact with almost every thing. So modelling it exactly is a detailed, difficult and inexact science.
I might take a look into wi-fi but in the field there is even no phone signal. That might create a problem I guess. We launched the rocket about a month ago, before flight you got about 5 to 10 minutes of time and the gps is fixing properly. And in the flight the gps is only important for the latest touch-down data. (We got gps coordinates with 2 meter error in the flight. It was pretty easy to find the rocket).
Strange. My wifi works quite well without any phone. Doesn't yours?